Why does it take so long to read PS games?

[Tonytone]

I've noticed when backing up PS1 or PS2 CD-ROM games, my Plextor 40/12/40 takes a very long time to read the original disc. Often times the speed is reduced to less than 1x, what gives?

How can I speed up the read process? And how do I judge the write speed using Verbatim DataSafe CD-R's?

TIA